Adjustable beds for hospitals have been made for some time and are well known in the art. Most of the present day adjustable beds provide some form of electronic control to adjust the various portions of the bed. Typically, a bed will have an up and down adjustment at the knee of the bed, at the head of the bed, and also for the entire bed frame. These different motors and drives, i.e. head, knee, and bed, are controlled by a wide variety of switch arrangments in the prior art. Some of these include simple manual controls for head up and down, etc. to what is known in the art as a Trendelenburg or reverse Trendelenburg which provides coordinated movement from more than one drive by pressing a single button on a control in order to move the bed into a flat, incline orientation with either the foot or the head elevated from the rest of the bed. Of course, all of these switches are well identified in the prior art to provide immediate information to both the patient and nurse which facilitates controlled movement of the bed into the desired position.
It is also well known in the art that switches to control movement of the various parts of the bed may be actuated either by hand or by foot. For those switches actuated by foot, it can be assumed that some selected patients would not have access to the foot controls, or at least are not readily accessible to a patient such that there is some discrimination in the prior art between those bed functions under patient control and those which are reserved for nurses' control. This is primarily for reasons of safety and to also minimize the tendency for a patient's curiosity with the controls to cause either damage to the bed or potential discomfort or even injury to the patient.
Because of the great concern for the safety of the patient, almost all of the beds in the prior art are provided with drives which move the bed relatively slowly to avoid sudden, rapid repositioning of the patient's body, or a jerky movement, either of which might potentially cause discomfort or even pain to the patient. While these features of the typical prior art bed are intended to provide for the increased comfort and safety of the patient, they are not the most desirable in all situations. For example, in an emergency situation, it would be most desirable to be able to quickly and easily, as well as automatically with hands free commands, reposition the bed from its existing position into an emergency position to facilitate the administering of CPR or other resuscitation efforts. At the same time, it is desirable to utilize a coded command which is not readily ascertainable from the markings on the switches and controls provided to the patient and, perhaps, to some of the staff.
To solve these and other problems in the prior art, and to also improve the functionality of an adjustable bed for emergency situations, the inventors herein have succeeded in designing and developing a control circuit which is operable by existing switches for providing an emergency re-positioning of the adjustable bed from its existing position into a CPR position which is characterized by a flat mattress surface at a specific height, e.g., the full up bed position. Furthermore, in order to provide greater safety and eliminate accidental or inadvertent commands, the inventors have chosen to require virtually simultaneous operation of a switch adapted for foot operation in combination with a switch adapted for hand operation. This renders it virtually impossible for a bed-ridden patient to enter the command, while at the same time requiring a staff member to thoughtfully and consciously utilize both his hand and foot in entering the command. Alternatively, any two switches could be used such as, for example, a pair of hand switches.
This control circuit is comprised of a logic circuit with an electronic timer at its heart along with several logic gates for decoding the coded command signal, and latching on the motors and drives for the various portions of the bed in their appropriate directions in order to automatically achieve the repositioning of the bed in its CPR position. The inventor herein has chosen to utilize the "bed up" foot control along with the "programmed Trendelenburg" or "programmed reverse Trendelenburg" hand switch for the coded command as these controls generally suggest the emergency CPR position in that the bed generally moves up from its existing position and the mattress surface is flat. However, any other combination of controls could be chosen to designate the same function. The timer is set to provide for each motor and its associated drive to travel through the full range of motion. Should the bed be oriented in an intermediate position, the automatic limit switch or mechanical cutouts for the bed drives will stop them in the desired orientation. Thus, the inventors have chosen to utilize a single timer which has a time delay long enough to ensure complete repositioning of the bed to the CPR position from a "worst case" orientation of the bed.
As the emergency CPR control circuit is fully compatible with existing controls and control circuits, and requires no additional mechanical switches or other controls, the inventor has been successful in adapting the entire circuit for mounting on a single PC card which may then be easily retrofitted to existing beds, as well as being easily incorporated into the manufacturing process presently used to manufacture new beds. This additional advantage lends great versatility to the inventor's improvement and provides wider application of the invention to a greater number of beds.
While the principal advantages and features of the present invention have been explained, a more thorough understanding thereof may be obtained by referring to the drawings and brief description of the preferred embodiment which follow.